Method and apparatus for forming a barrier layer on a substrate

1. A method of forming a barrier layer on a substrate, comprising:

sputter-depositing a tantalum nitride layer on a substrate having:

a metal feature formed on the substrate;

a dielectric layer formed over the metal feature; and

a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;

wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and

wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer, then back sputtering at least a portion of the tantalum nitride layer from the bottom of the via of the substrate; and

sputter-depositing a tantalum layer on the substrate, the tantalum layer having a thickness of less than about 100 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer;

wherein sputter-depositing the tantalum nitride layer and sputter-depositing the tantalum layer are performed in a single chamber.

2. The method of claim 1 , wherein the tantalum layer has a thickness of less than about 80 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.

3. The method of claim 2 , wherein the tantalum layer has a thickness of about 30-50 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.

4. The method of claim 3 , further comprising:

prior to the step of sputter-depositing the tantalum layer, back sputtering at least a portion of the tantalum nitride layer from the bottom of the via of the substrate.

5. The method of claim 4 , wherein the back sputtering step includes removing substantially all of the tantalum nitride layer from the bottom of the via.

6. The method of claim 5 , wherein the tantalum nitride layer has a thickness of about 200 angstroms or more on the field region of the dielectric layer after the back sputtering step.

7. The method of claim 6 , wherein the step of sputter-depositing the tantalum nitride layer has a duration of not more than about 10 seconds.

8. The method of claim 6 , wherein the back sputtering step has a duration of not more than about 15 seconds.

9. The method of claim 6 , wherein the step of sputter-depositing the tantalum layer has a duration of not more than about 2 seconds.

10. The method of claim 9 , wherein the step of sputter-depositing the tantalum layer has a duration of about 1 to 1.5 seconds.

11. The method of claim 2 , further comprising:

prior to the step of sputter-depositing the tantalum layer, back sputtering at least a portion of the tantalum nitride layer from the bottom of the via of the substrate.

12. The method of claim 1 , further comprising:

prior to the step of sputter-depositing the tantalum layer, back sputtering at least a portion of the tantalum nitride layer from the bottom of the via of the substrate.

13. The method of claim 12 wherein sputter-depositing the tantalum nitride layer, back sputtering at least a portion of the tantalum nitride layer and sputter-depositing the tantalum layer are performed in a single deposition chamber.

14. A method of forming a barrier layer on a substrate, comprising:

sputter-depositing a tantalum nitride layer on a substrate having:

a metal feature formed on the substrate;

a dielectric layer formed over the metal feature; and

a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;

wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and

wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer; and

back sputtering at least a portion of the tantalum nitride layer from the bottom of the via of the substrate; and

after the back sputtering step, sputter-depositing a tantalum layer on the substrate, the tantalum layer having a thickness of less than about 100 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer;

wherein sputter-depositing the tantalum nitride layer, back sputtering at least a portion of the tantalum nitride layer and sputter-depositing the tantalum layer are performed in a single deposition chamber.

15. The method of claim 14 , wherein the tantalum layer has a thickness of less than about 80 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.

16. The method of claim 15 , wherein the tantalum layer has a thickness of about 30-50 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.

17. The method of claim 14 , further comprising:

prior to the back sputtering step, sputter-depositing an initial tantalum layer on the substrate;

wherein the back sputtering step includes back sputtering at least a portion of the initial tantalum layer deposited prior to the back sputtering step.

18. The method of claim 14 , wherein the back sputtering step includes removing substantially all of the tantalum nitride layer from the bottom of the via.

19. The method of claim 18 , wherein the tantalum nitride layer has a thickness of about 200 angstroms or more on the field region of the dielectric layer after the back sputtering step.

20. A method of forming a barrier layer on a substrate, comprising:

sputter depositing a tantalum nitride layer on the substrate having:

a metal feature formed on the substrate;

a dielectric layer formed over the metal feature; and

a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;

wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer;

wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer; and

wherein the sputter depositing of the tantalum nitride layer is performed within a high density plasma physical vapor deposition (HDPPVD) chamber employing a plasma having an ion density of at least 10 10 ions/cm 3 , at a pressure of not more than about 10 mTorr using a target power of not more than about 40 kW and a pedestal bias power of not more than about 300 W;

back sputtering at least a portion of the tantalum nitride layer from a bottom of the via of the substrate within the HDPPVD chamber at a pressure of not more than about 10 mTorr using a target power of not more than about 1000 W, and a pedestal bias power of not more than about 1000 W; and

sputter-depositing a tantalum layer on the substrate at a pressure of not more than about 10 mTorr using a target power of not more than about 40 kW and a pedestal bias power of not more than about 300 W.